Process for improving artificial fibrous material



Patented Jan. 29, 1935 rnocnss non mrnovnm ARTIFICIAL mmous MATERIAL 1 Leon Lilienfeld,

Vienna, Austria NaDI-awing. Application May 29, 1929, Serial No. 367,154. n Austria June Is, 1928 11 Claims.

This invention is based on my discovery that artificial fibrous materials, for example, artificial silk, are in many respects improved in respect of their properties',-by treating them with one s or more substances having a basic reaction,- at a .high or moderately raised temperature. The most important basic substances for the purpose of this invention are solutions of caustic alkalies or'of alkali metal sulphides.

The improvements which are attained by the treatment of the artificial fibre (such as artificial silk), in accordance with thisinventionmay -be summarized as ,follows:

(1) The material acquires a soft, full, elastic feel approaching, and in some cases, equalling that of natural silk;

(2) The undesirable metallic lustre of the material is modified to give a'pleasing and more natural lustre and appearance, and may approach and in some cases equal the lustre of natural silk.

(3) The elasticity and extensibility of the material are increased.

(4) The undesirable tendency of the .material, in contrast with natural silk, to become creased, that is to show, in wearing, creases (particularly in the case of fabrics) which do not disappear by themselves, is very much diminished and in some cases altogether eliminated.

(5) The known difilculties experienced in mercerizing thecotton content of mixed fabrics or'of other mixed textiles consisting of cotton and artificial silk are eliminated by using alkali solutions or alkali metal sulphide solutions at a raised temperature for the mercerizatlon of such materials; hitherto these difilculties could be minimized only by artificial aids, such as a pretreatment of the artificial threads or fibers with a protective sizing or by the use of special mercerizing. solutions, containing an agent for preventing great injury to the artificial silk.

The invention has appreciable advantages in its application to the treatment of staple fibre and artificial wool; also these advantages reside essentially in an improvement in the feel of the material, in an increase in the elasticity and in a diminution in the tendency of the material to acquire permanent creases. My inves igations have, in fact, shown that the process of the invention is well suited for modifyingartificial silk so that it closely resembles natural silk in many of its properties.

Finally, it may be mentioned that it is indicated by my investigations that artificial silk which has been treated in accordance with this invention, has lost wholly or in considerable degree its tendency towards irregular absorption of dyestuffs.

The observation on which the invention is based, that the elasticity and feel of artificial fibrous material is appreciably improved by treatment with a hot solution of a caustic alkali or of an alkali metal sulphide of suitable concentration, without being considerably affected in respect of its-strength in the wet and in the PATENT OFFICE dry state and without destruction of its lustre,

the latter being in many cases improved, is surprising in view of the knowledge that solutions of caustic alkalies of the same concentration, (par- The invention consists in a treatment' of arti-v ficial fibrous material (including pureand mixed' fibres and fabrics, as hereinafter explained) with a solution of a basic. substance, particularly a solution of a caustic alkali or of an alkali sulphide, at a high temperature, for example at 50-l20 C. or higher, or at a moderately raised temperature, for example at -50 C.

The invention may be applied to viscose silk of any kind including the particular type of viscose silk (hereinafter referred to as Lilienfeld silk) made by spinning viscose in a bath containing a strong mineral acid, particularly strong sulphuric acid (as described for example in U. 8. Patents Nos. 1,683,199 and 1,683,200). It may alsobe applied to cuprammonium and silk, to nitro-silk (the above mentioned silks being composed essentially of cellulose or cellulose hydrate and are hereinafter included in the terms artificial fibrous material of regenerated cellulose and regenerated cellulose artificial silk, for

brevity) and when there is used a strong.solu-.v

tion of a caustic alkali (such as a solution containing more than about per cent. of caustic alkali, calculated as NaOH) or a strong solution of an alkali metal sulphide (such as a solution containing from 84 to -100 per cent. of sodium sulphide, calculated as the crystalline material, NazS-9H20) to acetate silk.

The invention is applicable not only to arti- I consisting wholly. of artificial fibres, and tomixed threads and fabrics, that is to say, to

threads and fabrics containing in addition to artificial fibres another fibrous material or materials, such as a mercerlzable fibre like cotton, or another fibre, such as natural silk, sheeps wool 01' the like. If wool or real silk is present they have to be protected against the action of the hot or warm solution of alkali by a suitable impregnation. The expression artificial fibrous material" as used in this specification and claims is intended to include artificial fibres (prepared from viscose, cuprammonium cellulose solution, nitrocellulose solution, cellulose acetate solution). The fibres maybe artificial silk, artificial cotton, artificial wool, artificial hair or artificial straw, these being in the form of spun material (threads. yarns in skeins or cope, or in the form of warm. twisted yarn or the like or in the form of fabrics) consisting of, or containing such spun materials. It includes ordinary viscose silk as well as "Lilienfeld silk.

Among the basic substances which find application in the invention, solutions of caustic alkalles and of alkali metal sulphides have been found especially advantageous; in the case of alkali metal sulphides, however, the concentration of the solution should not be less than 15 per cent., the sulphide being calculated as crystalline sodium sulphide. Solutions of other basic substances, however, may be used, such as I quaternary ammonium bases, organic bases (for example, guanidine) in whose aqueous solutions there may be presumed to be present a hydroxide which is strongly electrolytically dissociated or sulphonium hydroxides, such as trimethylsulphonium hydroxide.

The basic substance may be used in conjunction with a salt having a neutral or alkaline reaction (such as sodium chloride, sodium sulphate, sodium silicate, sodium aluminate, sodiacetate), or with a monohydric or polyhydric alcohol, such as ethyl alcohol or glycerin, a suitable quantity of the salt or alcohol being incorporated inthe solution of the basic substance.

The invention may be applied to finished artificial fibrous material initially, in the dry state, or in the wet or moist state; it may also be applied to artificial fibrous material which is not completely finished, for example, before or after the washing operation which succeeds the spinning of the fibre.

In cases in which a high elasticity is required of the treated material, the treatment is applied without subjecting the material to tension, or whilst subjecting it only to moderate tension.

The following Tables I and Ii illustrate how the invention may be carried out, and show the results obtained by treating artificial fibrous materials in accordance with the invention and, for comparison, the results obtained by a treatment conducted at ordinary temperature but under otherwise identical conditions;-

Table I In the Examples 1-20 described in the following 7 table, ordinary viscose silk (titre: deniers in 24-single filaments; strength in the dry state: 1.676 grams per denier; strength in the wet state: 0.600 grams per denier; extensibility: 24.2 per cent; elasticity: 8.2 per cent) was treated by immersion in the shrinking agents indicated in column 1 in the form of skeins without application of tension, at the temperature indicated in um zincate, borax, a sodium phosphate, sodium column 2 for the period indicated in column 3.

Strengthper s Shrinking n a 4 Em E xura on X nlasmph Wt I pera- 01.0mm After-treatment Lustre. Feel Titre Blbmty city Indry Inwet state state Deana 1 3- Per- Perprade Denim Gram: Grams cent cent 1 7%NaOH- 15 lminute... lminuteinbo Considerably Stifl 1.139 .348 17 5 water, wash destroyed. with cold water r and dried. 2 (in 25 do (in Hi2 S0! 168 1. 3418 476 34 1O 3 do 15 do 6 minutes in sulconsiderably Stifl. 168 1.308 .414 21 7 phuric acid of destroyed.

10 per' cent. strength at 16 0., 1 minute in bo ling water, wasbedwithcold water and dried 4 dn 25 do (in Fish Soft 164 1. 411 475 31 10 5 10%Ns011.- 15 ..do 5 minutes in sul- Destroyed wiry 192 0.897 .279 57.8 7.8

- phunc acid of 10 per cent. strength at 16 0., finally washed and dried it d 100 do do Com lately Extraordlna- 164 1.442 .472 27.8 9.2

re edand rilysoit and improved. elastic 7 12%NaOIL. 16 dn Practically Wlry 0.851 .316 I, 41.4 4.8

- destroyed 0 us. 8 do 100 do (10 Gem lately Bolt and elas- 164 1.463 .478 3.2 11.6

. re edand tic improved. 9 15%Na0lEL. 16 do do Very much Bolt 184 1.001 .343 42.4 7.3

diminished opaque. 10 do 100 do do Completely Soil; and elas- 164 l. 274 .446 30.6 13.3

retainedand tic. improved. 11---.- 18% NaOH. 16 do do Verymugg disomewhatsolt 184 1.115 .389 39.7 8.4 12 do 100 do do Completely Soft and elas- 164 1.350 .469 31.4 12.1

- retainedand tic.

- improved. 13--.-. MNaOH. 15 (in (In Vows; di- Slight] stil- 174 1.173 .392 37.1 6.8

en 14 do 100 do ,do Completely Holt and else- 166 1.355 .516 32 16 retamedand tic. improved.

' Strength per Ex Shrinking Duration dome E m Elas- I x nample agent m of action Lust" a sibllity ticity Indry Inwet state state Damn m m in a a 1; u a mm mm m: u 15--... -22 7 l5 1minute.. liminutee in sul- Verymuch di- Stlfl 178 1.165 .400 40.5 7.2 Ne lf. phuric acid 0110 minished.

pereentetre h at 15 C. y washed and dried. 16. do 120 do do Com lately Belt and else- 166 1.394 .462 30.1 11.5

I re nedand tic.

improved. NaOH. 100 an tin do do 153 1.492 .553 26.8 7.5 75 NaOH- 150 do do do do 160 1.537 .443 21.4 10.1 84 Nags... 100 fiminutesdo (in do 155 1.551 .588 30.3 9.7 1 ,,Na,8.- 100 (in do do do 162 1.506 .563 33.5 13.5

Table II case in a sulphuric acid bath of 55 36, according In the following table, the treatment was as indicated at the head of Table I, but the parent material was a number of samples or Lilienieldas silk, that is voscose silk made by spinning visto the process set forth in my U. S. Patents 1,683,199 and 1,683,200, above mentioned. For a further comparison are added the physical constants of the untreated material.

Example Shrinking agent Tem- tin-e Duration of action 7 Alter-treatment mime Feel

Strength per denier In wet state Extensibility Elasticity Untreate Degree: centigrade 7% NaOH-- 1 minute" Destroyed-.."

1 minutelminuteinboiling water, washed with cold water and dried.

Retained Soft 7% NnOH..-

Untreated 1 minute..

Washed with cold waterand dried.

Destroyed.--.-

Uni-manor? 1 minute W ashed with cold water and dried.

Retained 4' 7%NaOEL.

Untreated...

1 minute" 5 minutes in sulphuric acidoi 10 per cent. strength at 15 C .,wsshe dwith cold water and dried.

Destroyed".--

Very ooaree-.

i minute-.

5 minutes in sulphuric acid oi strength at 15 0.,weshed with cold water and dried.

Retained"-..

Very soft elastic and resemhiingreal silk.

7% NaH..

Untreated...

Untr

1 minute Destroyed still, hard,

coarse, lilaments pastedtogether.

1 minute..

minutes in sulphuric acid of 10 percent strength at 0., 1 minate in boilin water, wash with cold water and dried.

Retained 1 minute Completely destroyed.

Filaments are Denieri as a2 Grams Per- MOI

pasted together.

From the foregoing tables the following facts are evident at room temperature completely destroys the lustre of ordinary viscose silk and Lilienfeld-sllk. The same solution applied at 0. does not damage the lustre and does not considerably decrease the dry and wet tenacity; it increases the extensibility and elasticity to a great extent.

In the present process there may be used as treating baths, caustic alkali solution of any strength from 3 per cent. (calculated as NaOH) up to solutionssaturated at the temperature 'desired for the treatment, and alkali metal sulphide solutions of any strength from 15 per cent. (calculated as crystalline sodiinn sulphide, NazS- 9H2O) up to solutions saturated at the temperature desired for the treatment. And temperatures of from 25 to 160 C. may be employed-'- A solution of caustic soda of 8 per cent. strength 1 at room temperature completely destroys the lustre of ordinary viscose silk and of Lilienfeldsilk, and causes the silk to swell or dissolve to such an extent that the fibres are caused to adhere to each other. The same solution applied'at 100 C. does not damage the lustre; it decreases the strength in wet and dry condition in the case of ordinary viscose silk only inappreciably and in the case of Lilienfeld-silk not at all; it increases the extensibility of both kinds of silk very considerably and it scarcely affects the elasticity of the ordinary silk and increases that of Lilienfeldsilk very considerably.

A solution of caustic soda of 10 per cent. strength at ordinary room temperature destroys the lustre of ordinary viscose silk and of Lilien' field-silk, and causes an extraordinary decrease in the strength of both kinds of silk in thewet and dry state, so that the increase inextensibility-also produced is without value. The same solution applied at 100 0. causes no appreciable diminution in the lustre of either kind of silk, decreases only inappreciably the strengthsin the wet and dry state, and causes a considerable increase in the extensibility and elasticity.

A solution of caustic soda of 12 per cent. strength, at ordinary room temperature destroys the lustre of both kinds of silk and causes a great reduction in the strength in wet and dry state, and moreover, greatly diminishes the elasticity of or- .dinary viscose silk; all these disadvantages outweigh the value of the increased extensibility produced by the treatment. The same solution applied at 100 C. does not reduce the lustre of either kind of silk, reduces only slightly the and in the elasticity; the increase in extensibilitysimultaneously produced is therefore of no value. When the same solution is applied at 100 0., the

' lustre is retained, the strength in the wet and dry state sufiers an inappreciable diminution, and the 1 elasticity and extensibility are appreciably increased.

A solution of caustic soda of 18 per cent strength at 15 C. reduces considerably the lustre and the strength in the wet and dry state of ordinary vlscose silk, and has no appreciable effect on its elasticity; the increase in extensibility is, therefore, of noimportance. When the same solution is applied at 100 C. the lustre is preserved, the strength in wet. and dry state is slightly diminished, the extensibility is increased considerably and the elasticity very considerably.

A solution of caustic soda of 20 per cent. strength used at ordinary room temperature reduces the lustre of ordinary viscose silk and slightly reduces that of Lilienfeld-silk; in the case of ordinary viscose silk the strength in the wet and dry state is considerably decreased, and in the case of Lilienfeld-silk is decreased. but less considerably; the'extensibility of both kinds of silk is improved, but their elasticity is very considerably diminished. When the same solution is applied at 100 C. the lustre of both silks is unaffected, the decrease in their strengths in wet and dry state is very slight and the extensibility and elasticity increase, the latterby about 100 per cent. in the case of viscose silk. v

A solution of caustic of 22.5 percent.

strength at ordinary room temperature detracts from the lustre of ordinary viscose-silk and causes a considerable decrease in its strength in-wet and dry state, an increase in its extensibility and a 1 decrease in its elasticity. The same solution ap-' reduces the lustre of both kinds of silk, so that the increase in extensibility and elasticity are rendered valueless. When the same solution is .used at 100 0., both kinds of silk retain their original lustre, hardly suifer in respect of their strength, in the wet and dry state, and acquire a considerable increase in their extensibility and elasticity.

By treating an artificial silk fabric from ordinary viscose silk with a hot or warm solution of an alkali or alkali sulphide, in a manner similar to that described in the preceding examples, for instance, the following results are obtained:

A solution of caustic soda of 5'per cent. strength at 15 0. causes a strong diminution in the lustre and renders the material stiff and coarse to the feel. If the same solution is used at 100 0., the lustre is preserved and the material acquires a completely sillqr character, and a soft feel.

A caustic soda solution of '7 per cent. strength at 15 C. diminishes the lustre and makes the feel of the material very still. The same solution employed at 25 0., does not affect the lustre and imparts to the fabric a soft feel. i

A solution of caustic soda of 20 per cent, strength at ordinary temperature practically de stroys the lustre and confers on the material a stiff, coarse feel. If the same solution is used at 100 0., the metallic lustre gives place to a wholly silky appearance and thematerial becomes very soft to the feel. I

When using a solution of caustic soda of 50 percent. strength at 50 0., the lustre is practically the same as that of'natural, siIk and the material-acquires a very soft feel. If the same solution is applied at 100-440" 0., the material acquires a lustre which cannot be distinguished from that of natural silk, and its feel becomes soft and crackling.

Even caustic soda solutions of .74 per cent.

Solutions of sodium sulphide of 58, 84 and per cent. strength (calculated as crystalline NazS) s at 100-150 C. also confer upon fabrics of artificial silk a lustre which approaches or is even equal, t'o that of natural silk, and a very soft feel. A very important result of vthe treatment of artificial fibrous material with a warm or hot solution of an alkali or of an alkali sulphide, as described in the foregoing examples, is that the tendency of the material to form creases which do not disappear is very much diminished or even eliminated.

The treatment described in the foregoing examples may be applied to artificial fibrous material whilst this is subjected to tension, but the effects of the treatment, whilst they are still appreciable are less pronounced than when no tension is applied.

The treatment of spun or woven mixed materials containing artificial fibrous material, as well as the treatment of staple fibre, will be understood from the foregoing examples.

In the foregoing examples, instead of the temperatures given therein for the caustic soda solutions or sodium sulphide solutions, there may be used other temperatures, for example, any temperatures between 25 and 100 C.

In the foregoing examples, there may be used, instead of the solutions therein prescribed, a solution of another basic substance, for example, a solution-of guanidine of 20-50 per cent. strength, the temperature of'the treatment being, for ex ample, 25-100 0.; so also instead of a solution of caustic soda, there may be used a solution of another causticalkali, suchas a caustic potash solution of equivalent strength; and instead of. a solution of sodium sulphide a solution of another alkali metal sulphide may be used, such as potassium sulphide. There may also be used a strong solution of trimethyl-sulphonium hydroxide, of tetramethyl-ammonium hydroxide or the like.

' 'The treatment of artificial silk other than viscose silk, for example cuprammonium silk, is conducted in a similar manner, but it may be mentionedthat in the case of the treatment of cellulose acetate silk, the solution of the basic substance should be concentrated; for example, a caustic soda solution of 36 per cent. strength used'at 100 C. or of 50 per cent. strength used at 100-140 C. is suitable. 1

' Instead of transferring the artificial fibrous material directly from the hot alkali solutionto an acid bath, as describedin the examples, it may be introduced into cold or warm' or boiling water after being removed from the hot alkali solution (see, for instance, Examples 21, 22, 2'! and 28) and then washed, if required after being treated with an acid, and finally dried.

I claim: a

l. A process for treating artificial fibrous material of regenerated cellulose, which comprises, acting on said material with a solution selected from the herein described group consisting of .1,ea9,1oo

caustic. alkali solution of not less than 3% strength, calculated as NaOH, and alkali metal sulphide solution of not less than 15% strength, calculated as NazS-9H2O, and at a temperature not less than 50 C., thereafter washing and drying said material.

2. A process for treating artificial fibrous material, which comprises acting on said material with a solution of an alkali sulphide containing not less than 50 per cent. alkali sulphide (calculated as crystalline sodium sulphide) at a temperature of not less than 50 C.

3. A process for treating artificial fibrousv material produced by spinning viscose into a coagulating bath containing not less than 50 per cent. of H2804, which comprises acting on said material with an alkaline solution selected from the herein described group consisting of caustic alkali solution of at least 5% concentration, calculated as NaOH, and alkali metal sulphide solution of at least 15% concentration, calculated as Na2S-9H2O, which solution has a temperature not less than 50 C., thereafter washing and drying said material.

. 4. A process as in claim 3, wherein a caustic soda solution is used as the alkaline solution.

5. A process as in claim 3, wherein the artificial fibrous material after being treated with the alkaline solution is contacted with an acid solution and then washed and dried.

6. A process for treating artificial fibrous material produced by spinning viscose into' a coagulat ing bath containing not less than 50 per cent. of H2804, which comprises acting on said material with a solution of an alkali sulphide containing not less than 15 per cent. of alkali sulphide (calculated as crystallineNaaS) at a temperature of not less than 50 C. 1 V

7. A process as in claim 6, wherein the strength of the sodium sulphide solution (calculated as crystalline NazS) is not less than 50 per cent.

' 8. A process for treating artificialfibrous material produced by spinning viscose into a coagulating bath containing not less than 50 per cent. of H2804, which comprises acting upon said material with a solution consisting of melted crystalline sodium sulphide at about 100 C., thereafter washing and drying the material.

9. A process of improving cellulose acetate threads which comprises subjecting said threads tothe action of a treating solution selected from the group consisting of (a) caustic alkali solution of not substantially below 30% strength, calculated as NaOH, and (b) alkali metal sulphide solution of about 84 to 100%, calculated as NazS9I-I2O; such treatment being effected at a temperature not substantially below 50 C., and thereafter washing and drying the said threads.

10. A process as set forth in claim 3 in which a caustic alkali solution is used and in which the time of treatment does not exceed five minutes.

11. A process as set forth in claim 3 in which a caustic alkali solution is used having a strength of not less than 3 per cent (calculated as NaOH) and in which the time of treatment does not exceed five minutes.

LEON LILIENFELD. 

